Workers could be made redundant if it takes them longer to travel to the firmâs new base in Milton Keynes, according to the Transport Salaried Staffs Association.

The union claims 850 staff from Kent, Surrey, Sussex and Hampshire will be affected by the âunfair and arbitraryâ decision.

But Network Rail disputed the figure, saying only 150 people would be affected.

The company insisted it did not want to lose any staff and was working with individuals to encourage relocation and âmake help availableâ.

But the TSSA believes the move â which will come into force this summer â is unlawful and could lead to legal action.

General secretary Manuel Cortes said: âThis modern-day version of Beat The Clock to get to work is a complete nonsense.

âThey are telling staff they cannot follow their jobs in the worst recession in 70 years. With unemployment heading towards 3million, where else are they going to find work in these hard times?â

Dozens of offices from across Britain will be combined in Milton Keynes as part of plans to improve Network Rail efficiency and save taxpayers millions of pounds.

A spokesman said the move would be a âstep changeâ for the company and the travel time policy was part of attempts to âencourage the right kind of cultureâ.

But David Hodge, an employment law specialist from Brethertons Solicitors, said an employee who is willing to commute longer than the specified time limit but is still made redundant could claim unfair dismissal.

This would only be the case, however, if the employee had not been offered another suitable role at the Milton Keynes centre.

An Office for National Statistics report last year found that five per cent of Britons have a journey of an hour or more to work.